Telecommunications systems, cable television systems and data communication networks may use optical networks to rapidly convey large amounts of information between remote points. In an optical network, information may be conveyed in the form of optical signals through optical fibers. Optical fibers may comprise thin strands of glass capable of communicating the signals over long distances with very low loss. In the past, optical networks have employed a ring topology in which each node on the network connects to two other nodes. However, increases in traffic have necessitated the utilization of mesh topology. Mesh topology allows all nodes to be connected to each other. Such a configuration allows traffic to be rerouted as needed. Remote switching may be enabled using reconfigurable optical add/drop multiplexers (ROADMs).
The deployment of higher rate optical transmission at 40 Gigabits per second (Gb/s) and 100 Gb/s is driving the need for optical transport network (OTN) switching in core and metropolitan networks. OTN switching is able to groom a wide range of low-rate client traffic to efficiently fill 40 and 100 Gb/s line rate signals at the wavelength division multiplexing (WDM) layer (layer 1). Currently, traditional ROADMs are deployed at the WDM layer to provide full reconfigurability for transit wavelength channels but with fixed connectivity to specific node degree and wavelength for each add/drop port. Recent developments in ROADM technologies are enabling colorless, directionless (or non-directional), and contentionless features (CDC-ROADM) to also provide full reconfigurability between node degrees and add/drop ports. This flexibility of CDC-ROADMs may offer significant advantages in deploying future dynamic optical networks.